The subject matter disclosed herein relates generally to magnetic resonance imaging (MRI) systems and, more particularly, to systems and methods for performing diffusion weighted imaging (DWI) with an MRI system.
In general, magnetic resonance imaging (MRI) examinations are based on the interactions among a primary magnetic field, a radiofrequency (RF) magnetic field and time varying magnetic gradient fields with gyromagnetic material having nuclear spins within a subject of interest, such as a patient. Certain gyromagnetic materials, such as hydrogen nuclei in water molecules, have characteristic behaviors in response to external magnetic fields. The precession of spins of these nuclei can be influenced by manipulation of the fields to produce RF signals that can be detected, processed, and used to reconstruct a useful image.
Diffusion-weighted MRI techniques are known in the field of medical diagnosis and medical diagnostic imaging. For example, in some applications, MR DWI may be used as a non-contrast enhanced method for cancer imaging. In these applications, changes in DWI based diffusivity may correlate to the degree of response to cancer treatment, the diffusivity measured at baseline may be predictive of cancer treatment outcome, and so forth.
Conventional DWI techniques typically provide useful information about the diffusion properties of water in an organ of interest, but are associated with a variety of factors that may bias or distort the desired diffusivity measurement. For example, the accuracy and reproducibility of desired diffusion maps or coefficients may be affected by gradient non-linearity. For further example, errors may occur due to concomitant gradient fields (also commonly known as Maxwell fields) resulting from the applied diffusion gradient waveforms. Accordingly, there exists a need for improved systems and methods that address these drawbacks.